—In the Journal of last week (No. 23) was completed the essay of Dr. A. T. Keyt, of Cincinnati, Ohio, embodying the results of a most ingenious and extensive series of experimental investigations concerning the relations of cardiac action to pulse-wave velocity, cardio-aortic interval, etc., and the modifying effects of both stenosis and insufficiency at the mitral and aortic openings. If the three chapters are read together, it will be found that they embody the results of one of the most ingeniously conceived, patiently executed, and logically considered series of experimental investigations concerning important physiological and pathological processes that has appeared in this or any other country during the last decade. All parts of the essay are copiously illustrated by cuts giving the actual sphygmographic tracings and time markings, with remarkable accuracy. The more carefully and thoughtfully the essay is read, the more will its intrinsic value and interest be